PROJECT SUMMARY This is the application from the Division of Neonatology - Department of Pediatrics, University of Miami Miller School of Medicine for participation as a Clinical Research Center in the Prematurity-Related Ventilatory Control (Pre-Vent) cooperative program. Part of this proposal is a prospective study titled ?Oxygenation instability and maturation of control of breathing in evolving BPD?. Most extreme premature infants present with respiratory failure due to altered lung function compounded by breathing instability due to an immature respiratory control function. A significant proportion of these infants end up with abnormal lung development and bronchopulmonary dysplasia (BPD). Premature infants at risk for BPD present with significant oxygenation instability in the form of frequent spontaneous episodes of hypoxemia during the first weeks after birth. As a result, these infants receive oxygen supplementation but this is often excessive and these infants are also exposed to hyperoxemia. This is of great concern because studies in experimental animals have shown that exposure to intermittent hypoxia and hyperoxia can alter the normal development of their control of breathing system and contribute to respiratory instability. The extent to which these episodes of hypoxemia or the exposure to hyperoxemia impact on the maturation of the control of breathing system in extreme premature infants during the evolving stages of BPD is unknown. We propose a prospective study that will systematically evaluate such association in extreme premature infants at risk for BPD. The main objective of this study is to determine the extent to which exposure to frequent episodes of hypoxemia and hyperoxemia in extreme premature infants during the early stages of their chronic lung disease is associated with altered maturation and function of their respiratory control system. The causes for the altered maturation of the system that controls breathing in extreme premature infants with BPD are complex and not well understood and this hinders our ability to improve the care of these infants. Our overall goal is to participate in the Pre-Vent cooperative program and contribute to a better understanding of the factors that cause respiratory and oxygenation instability in premature infants with lung disease. Through this improved knowledge we expect to identify more effective preventive and treatment strategies for this vulnerable population.